Crawl space insulation

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  #1  
Old 09-24-02, 12:42 PM
mchan77
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Question Crawl space insulation

I think that there is moisture coming up from the crawl space under the house from water evaporating as evident by swollen hardwood floor boards, is there suppose to be insulation of somekind under there? If so, what is a recommended insulation and how should it be installed? I live in the San Francisco bay area. Thanks for any help, I want to get this done before it starts raining again.

Mike
 
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  #2  
Old 09-24-02, 04:31 PM
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Is the crawl space enclosed? Vented? Ground exposed? If the crawl space is enclosed, has the ground exposed in this enclosure, without venting, evaporation may be the cause. In which case all you have to do is prohibit the evaporation by laying plastic over the exposed ground. In most cases there are more concerns here than floor board swelling. Since they were not mentioned, I am assuming they don't exists.

Therefore I'll take a guess and say the home is air conditioned. The rule is warm air condenses against cooler surfaces, which would account for the floor boards swelling. Then insulation would prohibit the warm air touching the cooler floor boards created by the air conditioning.
 
  #3  
Old 09-25-02, 05:10 PM
gubs18
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similar problem

I have a similar problem in my bi-lvel; inside the hse, under the stairs leading to the 2nd floor, is an enclosed area (has a small trap door that is accessable thru a closet). the area is cinderblocked, unvented, cement floor & 3'x3' . no insulation of any type is there. in the winter the landing above this area gets very cold.

what is the best way to insultate this area pls?
 
  #4  
Old 09-25-02, 09:11 PM
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gub18

You could insulate the landing from the crawl space, underneath the stairs and the walls that separate the crawl space from the house. I would recommend rigid board insulation because it will be easy to install and inexpensive. You don't need that much insulation in that area, 1 inch board should suffice. You could even put it on the cinder block wall if you like. For the floor that small, use carpet.
 
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Old 09-26-02, 07:27 AM
gubs18
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Re: gub18: THANK YOU

THANK YOU VERY MUCH!!!
 
  #6  
Old 09-27-02, 09:55 AM
rbisys
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Greetings,

I'm an insuation contractor and I have developed a crawl space insulation method that has proven very effective.

The ground MUST BE DRAINED EFFICIENTLY or a sump pump installed.

Atrtach a 4 mil plastic sheet to the side of the plate sitting on the wall. Drape down and across the floor. Cover the remainder with same over lapping the seams about 6". Install second layer over the first, cross wise, but not up the wall.

It there is fiberglass in the spaces between the joists at the rim board remove it and replace with single layer radiant barrier(RB).

Attach over the plastic to the top board a 48" wide RB and let hang to floor. The temp in the crawl space will be within a couple of degrees of upstairs temp no moisture problems.

Seal any vents to the out side and foam ar caulk any hole along wall before starting.

4 mill plastic film base RBs are available for about $.20/ sf. If you have trouble finding, let me know.

DO NOT install fiber type material as it will quickly lose its values to moistue and you will have mold problems.

Thank you for considering my opinion.
 
  #7  
Old 09-28-02, 09:26 AM
gubs18
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sorry Rbisys - who's question were you answering?

Rbisys, was your response to the Gubs18 question, or Mchann77 or for both questions?

Gubs18's question was:
I have a similar problem in my bi-lvel: inside the hse under the stairs leading to the 2nd floor, is an enclosed area (accessable via small hatch thru a closet). the area is cinderblocked on one wall & studded on the others, it is unvented, has cement floor & is only 3'x3' . no insulation of any type in there; slight smell of moisture. in the winter the landing above this area gets very cold.

what is the best way to insultate this area pls?
 
  #8  
Old 09-29-02, 08:26 AM
rbisys
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Greetings,

Yes, those types of areas are a problem.

Ist off, since this is an enclosed small area without heat source or vent'n you it will always be cooler, even with RB.

I'm gussing the o/s wall is block which presents a problem because they are vapor porous. You can install a single layer (4mil) non-perforated over this wall, not letting it touch. For this small an area you could purchase the more expenive bubble foil locally.

Install a RB to the bottom of the step's runners.

For the floor two ways. Lay a RB on the floor and install a 1/2" OSB or similar over it. Attach 1x2" to bottom first to hold up off the RB (airspace).

Or, go to koolcoat.com and get some Rb paint beads and paint the floor. Buy enough so you can paint the rest of the interior walls of the house and drop your hvac loads considerabally.

Do not RB the interior wall of this space other than bottom of stair well.

Install a slated cover to provide some air and heat to area.

Don't forget RBs in the attic.

Moisture you smell is probably mold. Moisture doen't smell.


Thank you for considering my opinion.
 
  #9  
Old 10-07-02, 11:32 AM
wynnlwhite
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crawl spaces and moisture

Crawlspace moisture problems are like a jigsaw puzzle. Solutions generally come in more than one piece.

For sure, you don't want "free" water in the crawlspace--so exterior drainage is super important. Then, water from capillarity (from the soil) and from the outside air.

I recommend sealing the crawlspace off, putting a vapor barrier on the soil, sloping the floor to drain (pump the water out of the crawlspace if necessary), and dehumidifying the crawlspace.

Mold can grow at relative humidities of 70%--if you don't control moisture (and relative humidities) you will have problems.
 
  #10  
Old 10-07-02, 01:15 PM
rbisys
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Greetings,

If you install the radiant barrier system per my instuctions you will not have any moisture problems and no dehumidifyer is necessary.

This is a proven method. I've never had a failure.

Thank you.
 
  #11  
Old 11-08-02, 11:16 AM
rpenner
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Question

rbisys, I have a couple of questions about your method.

I have similar problems with my crawl space (moisture). The ground is exposed and there are a couple of vents on each side of the house. The main floor is heated with baseboards. I live in Canada where the winters are COLD.

Can I use your system in this situation? I currently have fiberglass between the joists at the sill plate. Should I remove it even in this cold climate?

Also, can you briefly describe this RB material. Is it rigid or like a poly plastic. I'm wondering if it is available up here and if it will be enough insulation for this area.

I also have fiberglass in some areas between the floor joists. Do you recommend removing this as well?

Thanks.
 
  #12  
Old 11-11-02, 06:12 PM
rbisys
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Greetings,

I thank you for your ?.

The FG can allow condensation to form on the wood any will cause rotting and mold problems. Replace it with a single RB sheet. I can assure you that the FG there is almost useless.
If you have plastic siding you can remove the lower three layers and install the RB to the out side wall covering the rim board area and the seam at the plate. This will decrease the air infiltration into the home and help the insulation there too.

The method I described will work in your area, HOWEVER, if it is extremely cold in your area you might want to cover the floor over the gravel and double plastic (4 mil) that should be there.

If you have my directions from previous you know what to do. If not let me know. BE SURE the area is well drained. The plastic can only do so much. You can seal the vents. Be sure to foam / caulk any cracks.

If you can't find a single layer material (flexiable like plastic film, about 4 mil thick) then I can supply you with it. 500 sf rolls at $.20/sf plus UPS. I haven't sent any to Canada so I don't know about shipping there or proper exchange procedure.

Check out Koolcoat.com also for upgrading the efficiency of your up stairs walls.

Have new computer and 1.3 camera. Hope to have pics available soon (?).

Thank you for considering my opinion.
 
  #13  
Old 11-12-02, 11:09 AM
rpenner
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Question

Someone suggested to me that I shold put rigid foam board insulation on the concrete walls as well. Any thoughts on this?

Also, once I have the plastic down, would it help to put a heater down there? In this climate, I find it hard to believe that it would stay within a few degrees of the inside house temp with just the RB for insulation.

Thanks.
 
  #14  
Old 11-16-02, 07:18 AM
rbisys
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Greetings,

Well guy, you won't know untill you try it. I've developed this method abot 10 years ago and it works just fine. Haven't found any thing better and I'm always open to new ideas.

By the way the foam is marginal at best. It is abouit 20% efficient.

Check the RB material available, seach; radiant barrier insulation.
 
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